PHD2 Misbehaving??!!

[Skipper Billy]

Out of all the challenges that imaging presents us with, guiding isnt normally an issue for me.

But tonight - nothing has been changed but PHD2 is all over the place.....

• Keeps telling me that the star has been lost - even though I can clearly see the star on the screen
• When it does guide its auto choosing a ridiculously dim star
• Then its massively overcorrecting giving a see saw graph
• More often than not it is choosing to guide on the edge or just off the edge of a star
• Multi star guiding isnt playing - it is just choosing one star

I have uninstalled the prog and reinstalled the latest version - just the same

Anyone have any ideas ???

I am imaging Meyers Nebula (IC2169), good seeing and transparency, not windy.

 

[tomato]

How is the seeing and sky transparency? Is the focus spot on? You have a Mesu so you could try extending the sub exposure time.

I think if you manually select a star while looping, PHD will use this star when you switch to guiding.

Hope you get it working, it’s a real pain to lose clear sky time to issues like this.

[Adreneline]

8 minutes ago, tomato said:

You have a Mesu so you could try extending the sub exposure time.

Picking up on @tomato's comment - I have an iOptron encoder mount and the advice I received from iOptron was to use the Delay feature in PHD rather than extending the exposure time; encoder mounts can exhibit a sort of 'hunting' behaviour where PHD is effectively fighting with the encoders. Sadly my iOptron mount failed before I got the chance to use this feature; previously I had never managed to get guiding working with my CEM25-EC.

I am aware you have had this working in the past so this may be a complete red herring but @tomato's prompted me to share what I had been told.

Adrian

[Guest]

First question, your version of PhD isn't the asiair, is it?  What you described matched almost exactly what happened to me the other night with my asiair.  Except for one thing I'll mention in a bit.

 

My two pennies worth.  What happened with my asiair was very similar.  It kept picking stars on the edge, picking relatively dim stars, then when the star brightness changed just a little (but still visible) it reported lost. In my case what was happening is I was using the guider chip at the very edge of the clear aperture of the scope (it's the 2600 duo, but think of it as an oag arrangement).  As the stars moved just a teeny bit across the chip the brightness would change enough to trigger phds star lost errors...as far as I can figure out.  This was especially apparent during the calibration phase when the star movement was tens of pixels.  I don't know if this applies to your case but maybe it does.

 

As to the large seesaw.  That happened to me on a different occasion and I figured out why.  In this case I was using a guidescopes in a fairly dense starfield. The star PhD chose to guide on had several other stars within the green guide box.  This would cause PhD to become confused and switch from one star to another within the box, causing those large seesaw errors like you mentioned.  My solution was actually to reduce exposure or gain until there were fewer stars in the field and less chance of two stars in the green guide box.  I don't know if this applies in your case either but worth mentioning I think.

 

 

[Skipper Billy]

13 hours ago, tomato said:

How is the seeing and sky transparency? Is the focus spot on? You have a Mesu so you could try extending the sub exposure time.

I think if you manually select a star while looping, PHD will use this star when you switch to guiding.

Hope you get it working, it’s a real pain to lose clear sky time to issues like this.

Cheers.

I took the opportunity of a semi clear night to recheck the PA - we had 5 earthquakes last week. It was nearly a degree out. All good after that at around ~0.4 RMS

Still guiding on the edge of a star though!

[Skipper Billy]

13 hours ago, Adreneline said:

Picking up on @tomato's comment - I have an iOptron encoder mount and the advice I received from iOptron was to use the Delay feature in PHD rather than extending the exposure time; encoder mounts can exhibit a sort of 'hunting' behaviour where PHD is effectively fighting with the encoders. Sadly my iOptron mount failed before I got the chance to use this feature; previously I had never managed to get guiding working with my CEM25-EC.

Oooh - I didnt know there is a delay feature - I will have to investigate! Cheers.

[Adreneline]

4 hours ago, Skipper Billy said:

I didnt know there is a delay feature - I will have to investigate!

HTH

[Skipper Billy]

@Adreneline Cheers!

[michael8554]

PHD2 can usually be left to chose the best star.

But maybe your star thresholds are incorrectly set.

Michael 

Edited February 8 by michael8554

[Skipper Billy]

54 minutes ago, michael8554 said:

PHD2 can usually be left to chose the best star.

But maybe your star thresholds are incorrectly set.

I think I am going to reset it back to factory and do a loooong 'Guiding Assistant' run.

It has always behaved impeccably and I think I must have inadvertently altered something but for the life of me I cant figure out what.